setting span multiplier to 1.0 so that user can set 0 to nyquist.

src/dtt/diag/ffttools.cc

@@ -31,7 +31,7 @@ namespace diag {
    // Time ahead buffers are allocated
    const double _TIME_AHEAD = 3.0; 
 
-   const double ffttest::fftSpanFactor = 1.1;
+   const double ffttest::fftSpanFactor = 1.0; //1.1;
 
    const fftparam ffttest::tmpresult::fftparamZero = {0, 0, 0, 0};
 
@@ -345,7 +345,7 @@ namespace diag {
          if (my_debug) cerr << "ffttest::calcTimes() return false line " << __LINE__ << endl ;
          return false;
       }
-   
+
       // highest frequency of interest
       if (fZoom != 0) {
          fMaxMeas = fSpan / 2.0;